‘Rosetta stone’ of code allows scientists to run core quantum computing operations

To build a large -scale quantum computer that works, scientists and engineers must overcome spontaneous errors that quantum bits, or qubits, create as they work.

Scientists code these elements constituting quantum information to delete errors in other qubits so that a minority can work in order to produce useful results.

As the number of useful (or logic) qubits increases, the number of physical qubits required increases even more. As this increases, the number of qubits necessary to create a useful quantum machine becomes an engineering nightmare.

Now, for the first time, quantum scientists of the Quantum Control laboratory at the University of Sydney Nano Institute have demonstrated a type of quantum logic door which considerably reduces the number of physical qubits necessary for its operation.

To do this, they built a logic door tangled on a single atom using an error correction code nicknamed the “rosetta stone” of quantum computer. He wins this name because he translates smooth and continuous quantum oscillations into clean and digital discreet states, which makes errors easier to spot and correct, and above all, allowing a very compact way to code logical qubits.

GKP codes: a rosetta stone for quantum computer science

The curiously named GOTTSMAN-KITAEV-PRESKILL (GKP) code has offered a theoretical possibility for significantly to considerably reduce the physical number of qubits necessary to produce a functional “logical qubit”. Although by exchanging the effectiveness of a complexity, which makes codes very difficult to control.

Research published in Nature physics Demonstrates it as a physical reality, explaining the natural oscillations of a trapped ion (an atom loaded with yterbium) to store GKP codes and, for the first time, making quantum tangled doors between them.

Directed by Dr. Tngei Tan Tin Tin from Sydney Horizon at Sydney Nano Institute, scientists used their exquisite control over the harmonic movement of a trapped ion to fill the coding complexity of GKP qubits, allowing a demonstration of their tangle.

“Our experiences showed the first realization of a universal logic door for GKP qubits,” said Dr. Tan. “We did it by precisely controlling natural vibrations, or harmonic oscillations, of an ion trapped in such a way that we can manipulate individual GKP qubits or tangle them in pair.”

Quantum logic door

A logic door is an information switch that allows computers – quantum and classic – to be programmable to carry out logical operations. The quantum logic doors use the entanglement of qubits to produce a completely different operational type of system to that used in conventional computers, underlying the great promise of quantum computers.

The first author Vassili Matsos is a doctorate. Student at the School of Physics and Sydney Nano. He said: “Indeed, we store two correctly error logical qubits in a single trapped ion and demonstrate a tangle between them.

“We did this using quantum control software developed by Q-CTRL, a start-up derived from the quantum control laboratory, with a model based on physics to design quantum doors that minimize the distortion of GKP logical qubits, they therefore maintain the delicate structure of the GKP code while processing quantum information.”

An important step in quantum technology

What Mr. Matsos has done is tangled on two “quantum vibrations” of a single atom. The three -dimensional trapped atom vibrates. The movement in each dimension is described by quantum mechanics and each is considered a “quantum state”. By preventing two of these quantum states carried out as a quit, Mr. Matsos has created a logical door using a single atom, an important step in quantum technology.

This result massively reduces the quantum material required to create these logic doors, which allow the programming quantum machines to be scheduled.

Dr. Tan said: “GKP error correction codes have long promised a reduction in material requests to take up the challenge of the general resources for the quantum computers scale. Our experiences have reached a key step, demonstrating that these high quality quantum commands provide a key tool to manipulate more than one logical qubit.

“By demonstrating universal quantum doors using these qubits, we have a basis for working to process quantum information on a large scale in a very economical equipment.”

Through three experiments described in the article, Dr Tan’s team used a single Ytterbium ion contained in what is known as a Paul trap. This uses a complex range of lasers at room temperature to maintain the unique atom in the trap, allowing its natural vibrations to be controlled and used to produce complex GKP codes.

This research represents a significant demonstration that quantum logical doors can be developed with a reduced physical number of qubits, increasing their effectiveness.